| 13441 | 14 Mar 26 | 2026 Oro Valley Triathlon & Duathlon Festival | triathlon | Oro Valley, AZ |
| 13442 | 25 Apr 26 | 2026 Orange County Triathlon & Duathlon | triathlon | Mission Viejo, CA |
| 13443 | 29 Mar 26 | 2026 Operation Enduring Warrior 5k/10k/Half | 10K/13.1/5K | Potomac, MD |
| 13444 | 30 May 26 | 2026 OnondagaMan Half Iron | triathlon | Jamesville, NY |
| 13445 | 17 May 26 | 2026 Onion Man Triathlon | triathlon | Walla Walla, WA |
| 13446 | 20 Sep 26 | 2026 Oktoberfest Sprint Triathlon - Longmont | triathlon | Longmont, CO |
| 13447 | 18 Sep 26 | 2026 Oktoberfest 5k & 10k | 10K/5K | Alexandria, VA |
| 13448 | 26 Nov 26 | 2026 Oklahoma City Turkey Trot | 5K | Oklahoma City, OK |
| 13449 | 11 Jul 26 | 2026 Oconto Falls Dri - Tri | triathlon | Oconto Falls, WI |
| 13450 | 25 Oct 26 | 2026 Ocean State Rhode Races - Marathon, Half Marathon and 5k | 5K | Narragansett, RI |
| 13451 | 24 Sep 26 | 2026 Northwest Series - Day 6 (ID) | 5K/10K | Lewiston, ID |
| 13452 | 23 Sep 26 | 2026 Northwest Series - Day 5 (ID) | 5K/10K | Lewiston, ID |
| 13453 | 22 Sep 26 | 2026 Northwest Series - Day 4 (WA) | 5K/10K | Clarkston, WA |
| 13454 | 21 Sep 26 | 2026 Northwest Series - Day 3 (WA) | 5K/10K | Clarkston, WA |
| 13455 | 21 Feb 26 | 2026 Northeast Park Duathlon | triathlon | Gibsonville, NC |